On Mar. 10, 1970, applicant was awarded U.S. Pat. No. 3,499,432, entitled Heating Unit. This patent disclosed a wood burning fireplace employing a firebox supported on a vertical pedestal. A vertical hollow cylinder formed primarily of glass, open at upper and lower ends, and having at least one vertical air intake slot was secured at its lower end to the firebox and extended upward. A vertical hollow truncated cone open at both ends was secured at its bottom and larger end to the upper end of the cylinder and has a chimney or smokestack in its top and smaller end. When fuel is burned in the firebox, the air entering swirls upward in a generally helical pattern of ever decreasing diameter, providing an enhanced lighting effect and keeping the windows clear and free of smoke.